Kepler-93b
{{Short description|Super-Earth exoplanet in constellation Lyra}}
{{Infobox planet
| name = Kepler-93b
| discoverer = Geoffrey W. Marcy et al.
| discovered = February 2014 (announced)
| discovery_method = Transit method
| image = Image:Comparison Kepler-93b & Earth.jpg
| caption = An artist's impression comparing the size and internal structure of Earth (left) and Kepler-93b (right).
| alt_names = KIC 3544595 b, KOI-69.01, BD+38 3583b, TYC 3134-218-1 b{{cite web |title=The Extrasolar Planet Encyclopaedia — Kepler-93b |url=https://exoplanet.eu/catalog/kepler_93_b--2275/ |work=Extrasolar Planets Encyclopaedia |access-date=2024-05-04}}
| apsis = astron
| semimajor = {{val|0.05343|0.00065|ul=AU}}
| eccentricity = 0
| period = {{val|4.72673978|(97)|ul=d}}
| inclination = {{val|89.183|0.044|u=deg}}
| semi-amplitude = {{val|1.89|0.21|ul=m/s}}
| star = Kepler-93
| mean_radius = {{val|1.478|0.019|ul=Earth radius}}
| mass = {{val|4.66|0.53|ul=Earth mass}}
| density = {{val|7.93|0.96|0.94|ul=g/cm3}}
| single_temperature = {{val|1133|17|ul=K}} ({{convert|1133|K|C F|disp=out}}, equilibrium)
}}
Kepler-93b (KOI-69b) is a hot, dense transiting Super-Earth exoplanet located approximately {{convert|313|ly|pc|lk=on|abbr=off}} away in the constellation of Lyra,{{cite web |title=BD+38 3853 |url=https://simbad.u-strasbg.fr/simbad/sim-id?Ident=+BD%2B38+3583 |work=SIMBAD |access-date=2024-05-08}}{{cite web |title=SKY-MAP.ORG - Interactive Sky Map |url=http://www.sky-map.org/ |work=Sky-Map.org |access-date=2024-05-08}} orbiting the G-type star Kepler-93. Its discovery was announced in February 2014 by American astronomer Geoffrey Marcy and his team. In July 2014, its radius was determined with a mere 1.3% margin of error, the most precise measurement ever made for an exoplanet's radius at the time.
Physical properties
The planet has a radius of around 1.478 {{Earth radius|link=y}} (9,416 km), with an uncertainty of just 0.019 {{Earth radius|link=y}} (121 km), making it the most precisely measured exoplanet ever in terms of radius as of July 2014.{{cite web |url=https://www.nasa.gov/image-article/gauging-an-alien-worlds-size/ |title=Gauging an Alien World's Size |author= |date=2014-07-22 |publisher=NASA |access-date=2024-05-07}} The planet is substantially denser than Earth at {{val|6.88|1.18|u=g/cm3}} thanks to its high mass of roughly 4 {{Earth mass|link=n}}, consistent with a rocky composition of iron and magnesium silicate. In 2023, the planet's mass was revised upward to 4.66{{±|0.53}} {{Earth mass}}, placing its density at 7.93{{±|0.96|0.94}} g/cm3, roughly the same as the metal iron ({{val|7.874|ul=g/cm3}}).{{cite book |last=Arblaster |first= John W. |title=Selected Values of the Crystallographic Properties of Elements |publisher=ASM International |publication-place=Materials Park, Ohio |date=2018 |isbn=978-1-62708-155-9}}
Based on these findings, the interior of the planet is likely similar to that of Earth and Venus, with an iron core making up around 26% of its total mass (albeit with a large uncertainty of ±20%), compared to the 32.5 ± 0.1% of Earth and 31 ± 1% of Venus.{{cite journal | title=Mass-Radius Relation for Rocky Planets based on PREM | display-authors=1 | last1=Li | first1=Zeng | last2=Sasselov | first2=Dimitar | last3=Jacobsen | first3=Stein | journal=The Astrophysical Journal | volume=819 | issue=2 | id=127 | date=March 2016 | doi=10.3847/0004-637X/819/2/127 | bibcode=2016ApJ...819..127Z | arxiv=1512.08827 | s2cid=119111854 | doi-access=free }}
The planet orbits its host star every 4.73 days at a distance of {{convert|0.05343|AU|km|abbr=on}}, less than one-seventh the radius of Mercury's orbit. Its equilibrium temperature is approximately {{convert|1133|K|C F|abbr=on}}, which is as hot as lava and well above the melting point of aluminium.{{efn|The temperature of lava is typically at {{convert|800|-|1200|C|K F}}; aluminium melts at {{convert|660.32|C|K F}}.}}
Host star
The planet orbits a Sun-like (spectral type G5V) star named Kepler-93. The star has a mass of 0.911 {{Solar mass|link=y}} and a radius of 0.919 {{Solar radius|link=y}}. It has a temperature of {{convert|5669|K|C F}} and is 6.6 billion years old. In comparison, the Sun is 4.6 billion years old,{{Cite journal |last1=Connelly |first1=JN |last2=Bizzarro |first2=M |last3=Krot |first3=AN |last4=Nordlund |first4=Å |last5=Wielandt |first5=D |last6=Ivanova |first6=MA |date=2 November 2012 |title=The Absolute Chronology and Thermal Processing of Solids in the Solar Protoplanetary Disk |journal=Science |volume=338 |issue=6107 |pages=651–655 |bibcode=2012Sci...338..651C |doi=10.1126/science.1226919 |pmid=23118187 |s2cid=21965292}}{{Registration required}} has a temperature of {{convert|5772|K|C F}} and a spectral type of G2V.{{Cite web |last=Williams |first=D.R. |date=1 July 2013 |title=Sun Fact Sheet |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html |url-status=live |archive-url=https://web.archive.org/web/20100715200549/http://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html |archive-date=2010-07-15 |access-date=2013-08-12 |publisher=NASA Goddard Space Flight Center}} The apparent magnitude of the star is 9.931, making it too dim to be visible from Earth by the naked eye.{{cite web|date = February 2001|title = The Bortle Dark-Sky Scale|publisher = Sky & Telescope|author = John E. Bortle|url = http://www.skyandtelescope.com/resources/darksky/3304011.html|access-date = 2009-11-18|archive-url = https://web.archive.org/web/20090323232806/http://www.skyandtelescope.com/resources/darksky/3304011.html|archive-date = 2009-03-23|url-status = dead}}
The star is host to an additional non-transiting confirmed companion, Kepler-93c, which was discovered using the radial-velocity method and announced in 2014, concurrently with Kepler-93b. The object is most likely a brown dwarf orbiting much farther out than Kepler-93b, though its precise nature remains uncertain. The discovery paper reported a lower limit on the mass of 3 {{Jupiter mass|link=y}} and a minimal orbital period of {{convert|1460|d|year|abbr=off}}, while a subsequent study in 2015 weighed the planet at >8.5 {{Jupiter mass}} and presented an orbital period of >10 years, placing its orbit beyond 4.5 AU from the star, and a 2023 study increased these lower limits further, to a mass >21 {{Jupiter mass}}, an orbital period >48.6 years, and a semi-major axis >13 AU.
See also
- List of exoplanets discovered by the Kepler space telescope
- List of transiting exoplanets
- Other dense super-Earths orbiting close to their parent stars:
- CoRoT-7b, has a similar radius to Kepler-93b, but is more massive and much hotter.
- HD 219134 b, has a similar radius, mass and temperature.
- Kepler-10b, has a similar radius, but is slightly less massive and much hotter.
- Kepler-36b, has a similar radius, mass and temperature.
Footnotes
{{noteslist}}
References
{{reflist|refs=
{{Cite Gaia DR3|2052747119115620352}}
{{cite journal | title=Kepler-93b: A Terrestrial World Measured to within 120 km, and a Test Case for a New Spitzer Observing Mode | display-authors=1 | last1=Ballard | first1=Sarah | last2=Gilliland | first2=Ronald L. | last3=Kjeldsen | first3=Hans | last4=Christensen-Dalsgaard | first4=Jørgen | last5=Charbonneau | first5=David | last6=Désert | first6=Jean-Michel | last7=Huber | first7=Daniel | last8=Chaplin | first8=William J. | last9=Basu | first9=Sarbani | last10=Fressin | first10=Francois | last11=Li | first11=Zeng | last12=Werner | first12=Michael W. | last13=Davies | first13=Guy R. | last14=Aguirre | first14=Victor Silva | last15=Metcalfe | first15=Travis S. | last16=Stello | first16=Dennis |last17=Bedding | first17=Timothy R. | last18=Campante | first18=Tiago L. | last19=Handberg | first19=Rasmus | last20=Karoff | first20=Christoffer | last21=Elsworth | first21=Yvonne | last22=Hekker | first22=Saskia | last23=Kawaler | first23=Steven D. | last24=Lund | first24=Mikkel N. | last25=Lundkvist | first25=Mia |journal=The Astrophysical Journal | volume=790 | issue=1 | id=12 | date=July 2014 | doi=10.1088/0004-637X/790/1/12 | bibcode=2014ApJ...790...12B | arxiv=1405.3659 | s2cid=12644226 | doi-access=free }}
{{cite journal | title=The Mass of Kepler-93b and The Composition of Terrestrial Planets | display-authors=1 | last1=Dressing | first1=Courtney D. | last2=Charbonneau | first2=David | last3=Dumusque | first3=Xavier | last4=Gettel | first4=Sarah | last5=Pepe | first5=Francesco | last6=Cameron | first6=Andrew Collier | last7=Latham | first7=David W. | last8=Molinari | first8=Emilio | last9=Udry | first9= Stéphane | last10=Affer | first10=Laura | last11=Bonomo | first11=Aldo S. | last12=Buchhave | first12=Lars A. | last13=Cosentino | first13=Rosario | last14=Figueira | first14=Pedro | last15=Fiorenzano | first15=Aldo F. M. | last16=Harutyunyan | first16=Avet | last17=Haywood | first17=Raphaëlle D. | last18=Johnson | first18=John Asher | last19=Lopez-Morales | first19=Mercedes | last20=Lovis | first20=Christophe | last21=Malavolta | first21=Luca | last22=Mayor | first22=Michel | last23=Micela | first23=Giusi | last24=Motalebi | first24=Fatemeh | last25=Nascimbeni | first25=Valerio | last26=Phillips | first26=David F. | last27=Piotto | first27=Giampaolo | last28=Pollacco | first28=Don | last29=Queloz | first29=Didier | last30=Rice | first30=Ken | last31=Sasselov | first31=Dimitar | last32=Ségransan | first32=Damien | last33=Sozzetti | first33=Alessandro | last34=Szentgyorgyi | first34=Andrew | last35=Watson | first35=Chris |journal=The Astrophysical Journal | volume=800 | issue=2 | id=135 | date=February 2015 | doi=10.1088/0004-637X/800/2/135 | bibcode=2015ApJ...800..135D | arxiv=1412.8687 | s2cid=53471038 | doi-access=free }}
{{cite journal |last1=Bonomo |first1=A. S. |last2=Dumusque |first2=X. |display-authors=etal |date=September 2023 |title=Cold Jupiters and improved masses in 38 Kepler and K2 small planet systems from 3661 HARPS-N radial velocities. No excess of cold Jupiters in small planet systems |journal=Astronomy & Astrophysics |volume=677 |issue= |pages=A33 |doi=10.1051/0004-6361/202346211 |arxiv=2304.05773 |bibcode=2023A&A...677A..33B |s2cid=258078829}}
}}
{{exoplanets}}
{{Lyra}}
{{2014 in space}}
Category:Exoplanets discovered in 2014
Category:Exoplanets discovered by the Kepler space telescope